Tawdeze kear drive j



A. H. LEIPERT.

l ,402, 30 1 Patented Jan. 3, 1922.

w/mfss l I j l Aron `Br l we A TTBNE YS ,man STATES PATENT OFFICE.

AUGUST H. LEIPERT, OF NEW YORILIN. Y., ASSIGNOR TO INTERNATIONAL MOTORCOMPANY, OF NEW YORK, N. Y.,

A. CORPORATION OF DELAWARE.

TANDEM REAR DRIVE FOR MOTOR VEHICLES.

LIOMI.

Application filed .Tune 7,

To all fui/tom t may concer/'a Be it known thatI, AUGUST H. Lnirnn'r, acitizen of the United States, residing in the borough of Queens, of thecity of New York, in the State of New York, have invented certain newand useful Improvements in riandem Rear Drives for Motor Trucks, ofwhich the following is a specification, reference being had to theaccompanying drawing, iorming a part hereof.

The advantages oi so-called tandem rear drives ll'or motor vehicles inwhich a plurality et drive wheels is employed have been long recognizedin the automotive industry. rIhe saving in weight, the saving in tiresand the reduction in heavy wheel loads on roads are advantages ofconsiderable importance over the usual two-drive wheels which constitutethe main load carrying wh eels in ordinary constructions. However, thepractical results achieved in drives ot this type have been limited duein a large measure to a positive interconnection of the several drivewheels in such manner as to prevent independent differential movement asbetween any two of the wheels. In the drives employed it has beenproposed merely to duplicate for each pair of wheels the usualdiiierential element therebetween but no provision has been made fordierential movement as between the drive shafts of different pairs ofwheels. In accordance with the present invention it is proposed toovercome the objections which have been found in practise to knownconstructions by introducing operatively between the drive shafts otdierent pairs of wheels differential gearing which will permit at alltimes ready diierential movement between any two-ot the shafts employedin propelling the vehicle. 'Ihis construction may be embodied in man)`Vdifferent forms and it is not proposed b v the accompanyingillustrations of one embodiment to limit the precise means forpractising the invention. In the drawing- Figure l is a view somewhatschematic one of the side 'frame members of a motor truck in which areemployed tandem rear wheels, one of the wheels oi each of the pair beingillustrated.

Figure 2 is a detail view in section show- Specification of LettersPatent.

Patented Jan. 3, 1922. 1920. serial No. 386,951.

ing the means for interposing differential gearing between the drivingunits ol the two pairs ofwheels.

As the description proceeds it will become evident that the invention isnot to be limited to the employment of only two pairs of drive wheels ina vehicle since the number oi' pairs can be multiplied and theimprovements associated with all such pairs. Nor is theinvention to belimited to any particular form of drive -nor to the relationship ofparts in the vehicle structure. A conventional type of vehicle and driveis illustrated.

In the drawing, one of the side frame members a of a motor truck isshown as supported by means of dual springs b the ends of which arecarried on dead axles c, e for the drive wheels f, g, respectively. Thedrive wheels are mounted at the ends of the axles c, c, in pairs and theillustrated drivecan be considered as a tandem drive in that two suchpairs are employed. The wheels of each pair are driven by axle sections,one of which for each pair is illustrated at ff g. Two such axlesections are provided for each pair of wheels and are operativelyconnected at their proximate ends to a differential gear, one of which,for the axle section g, is indicated conventionally at h. Thediferential gear h has a master gear h thereon engaged by a driving gearwhich in the illustrated embodiment is a worm z'. The differential gearfor the axle section f is illustrated conventionally at 7c and itsmaster gear at c.

The propeller shaft of the vehicle is illustrated at Z. Known types ofdrives, whether of the worm, bevel gear or chain type, have usuallytaken the power from the propeller shaft Z to the diierential gears forthe pairs of wheels, so that differential movement between each of thewheels of a pair would be permitted in accordance with common practise.However, such differential gears have, as to each other, been positivelyinterconnected so as to be driven at all times at -equal speeds and withequal torque effort strains and speeds therebetween in accordance withtraction conditions of the different wheels. One means forlprovidingsuch differential movement is illustrated in the drawings. In this casethe propeller shaft Z has keyed thereto a differential housing m inwhich are supportedV a plurality of planetary pinions m. These pinionsmesh with driving bevel gears n, o in a manner commonly employed indifferentials of this type, one of these driving gears n being keyed toa solid drive shaft n which is keyed to the worm z' for one pair ofwheels g, and the other of said bevel gears o being keyed to a hollowshaft o carrying a driving worm p which meshes with the driving gear cfor the differential la. The worm p may be formed integral with ormerely secured to the shaft o. The solid shaft n in the illustratedembodiment extends through the hollow shaft o.

The shaft n is preferably formed sectionally and has interposed thereinbetween the worms z' and p a universal joint n2 which permits a degreeof relative movement between the dead axles c, e and the associatedparts.

From the description given it is believed that the operation will beapparent. Power is delivered from the propeller shaft Z through thedifferential housing m and ear n to the drive shaft In for the worm i.

ower is also delivered through the differential m and gear 0 to thedrive shaft o" for the worm p. The proportion of power delivered to thetwo differentials k, h in this manner will depend on the usual variablefactors in vehicle drives, but that degree of flexibility as betweendriving units is afforded which is necessary for a correct apportionmentof ower.

Not only `is di erential movement permitted as between the .two wheels gof Aa pair, as by means of the differential gear h, or between the twowheels f of the other air, as by means of the differential gear k,

ut differential movement is rmitted as between either one of the sha tsections f or g by reason of the operative interposition therebetween ofthe differential gear m.

As pointed out before the necessary freedom of movement as between thetwo axle sections c, e, and their associated parts is afforded by theuniversal joint n2 in the sectional shaft n.

The scope of the invention will appear from the appended claims.

I claim as my invention:

l. In a motor truck, a plurality'of pairs of drive wheels, driving axlesections for each of the wheels, differential gears interposed betweenthe axle sections of each pair of wheels,a propeller shaft, and adifferential gear and shafting aligned with the propeller shaftinterposed operatively between said propeller shaft and said first nameddifferential gears, respectively.

2. In a motor truck, a plurality of pairs of drive wheels, driving axlesections for each of the wheels, differential gears interposed betweentlie axle sections of each pair of wheels, a propeller shaft, a secondshaft disposed in substantial alignment with said propeller shaft, andan operative connection between the propeller shaft and each of saiddifferential gears including a differential gear and said aligned shaft,said propeller shaft being connected to the housing of thelast nameddifferential to rotate it and the respective gears within the last nameddifferential having operative connections, includin said aligned shaftto the two first name differential gears.

3. In a motor truck, a tandem rear drive comprising the dead axles onwhich the pairs of wheels are mounted, driving shaft sections for eachof the wheels, a differential gear to which the pairs of dead axles areconnected, a worm gear carried by each differential gear, a worinmeshing operatively with said worm gears respectively, a hollow shaft onwhich one of said worms is carried, a solid shaft extending through saidhollow shaft and engaged with the other of said worms, a universal jointin said last named shaft, a differential gear including planetarypinions, a propeller shaft connected operatively with said planetarypinions and two driving gears engaged by said pmions, one of said gearsbeing keyed to the said solid shaft and the other of said gears beingkeyed to said hollow shaft.

This specification signed this 4th day of June, A. D. 1920.

AUGUST H. LEIPERT.

